Systems and methods for monitoring temperature using acoustic waves during processing of a material

Abstract

Under one aspect, a method of processing a material includes heating a region of the material with a first energy source; exciting an acoustic wave in the material; and transmitting the acoustic wave through the heated region, the heated region changing at least one property of the acoustic wave. The method also can include detecting the change in at least one property of the acoustic wave; characterizing a temperature of the material in the heated region based on the detected change in at least one property of the acoustic wave; and comparing the characterized temperature of the material in the heated region to a threshold. The method further can include, based on the characterized temperature of the material in the heated region being less than the threshold or being above the threshold for an insufficient amount of time, modifying a property of the heated region with a second energy source.

What is claimed: 
     
       1. A method of processing a material, the method comprising:
 heating a first region of the material with a first energy source; 
 exciting a first acoustic wave in the material; 
 transmitting the first acoustic wave through the heated first region of the material, the heated first region of the material changing at least one property of the first acoustic wave; 
 detecting the change in at least one property of the first acoustic wave; 
 characterizing a temperature of the material in the heated first region based on the detected change in at least one property of the first acoustic wave; 
 comparing the characterized temperature of the material in the heated first region to a threshold; and 
 based on the characterized temperature of the material in the first region being less than the threshold or being above the threshold for an insufficient amount of time, modifying a property of the heated first region with a second energy source. 
 
     
     
       2. The method of  claim 1 , further comprising, responsive to heating the first region of the material with the first energy source, melting a powder or a wire in the first region to form the material. 
     
     
       3. The method of  claim 1 , further comprising, responsive to heating the first region of the material with the first energy source, excising a portion of the material. 
     
     
       4. The method of  claim 1 , wherein the acoustic wave comprises one or more of a surface acoustic wave, a bulk acoustic wave, a guided acoustic wave, and a phonon. 
     
     
       5. The method of  claim 1 , further comprising:
 characterizing a defect in a morphology of the material in the heated first region based on the detected change in at least one property of the first acoustic wave; and 
 based on the characterized defect, heating the first region of the material to a temperature above the threshold with the second energy source. 
 
     
     
       6. The method of  claim 1 , wherein modifying the property of the heated first region with the second energy source comprises heating the first region of the material to a temperature above the threshold. 
     
     
       7. The method of  claim 1 , further comprising:
 exciting a second acoustic wave in the material; 
 transmitting the second acoustic wave through a heated second region of the material, the heated second region of the material changing at least one property of the second acoustic wave; 
 detecting the change in at least one property of the second acoustic wave; 
 characterizing a temperature of the material in the heated second region based on the detected change in at least one property of the second acoustic wave; 
 comparing the characterized temperature of the material in the heated second region to a threshold; and 
 based on the characterized temperature of the material in the second region being less than the threshold or being above the threshold for an insufficient amount of time, modifying a property of the heated second region with the second energy source or with a third energy source. 
 
     
     
       8. The method of  claim 1 , wherein the change in at least one property of the first acoustic wave comprises a change in an arrival time, a change in a disturbance amplitude, or changes both in the arrival time and the disturbance amplitude, of at least one frequency component of the first acoustic wave. 
     
     
       9. The method of  claim 8 , wherein detecting the change in the arrival time, the change in the disturbance amplitude, or the changes both in the arrival time and the disturbance amplitude, of the at least one frequency component of the first acoustic wave comprises receiving laser light reflected from the material. 
     
     
       10. The method of  claim 1 , wherein the first energy source comprises a first laser or a first particle beam. 
     
     
       11. The method of  claim 10 , wherein the first laser excites the first acoustic wave. 
     
     
       12. The method of  claim 10 , wherein the second energy source comprises a second laser or a second particle beam that is discrete from the first laser or the first particle beam.